In order to deal with increasingly rampant terrorism activities worldwide, all nations are striving to strengthen security inspection of goods imported and exported, particularly of container trucks. Terrorists often smuggle dangerous articles such as explosives, guns or the like through seaports or the Customs and so on, which causes a great threat to a nation's security. The above phenomena can be avoided to a large extent by means of detection of a radiation scanning imaging system. The inspection system of this kind is characterized in that a special scanning device emits rays for radiation scanning of a container truck to be inspected, the scanning device is equipped with a radiation source and some detectors, and in that the container truck is scanned by the scanning device which reciprocatingly moves. The rays emitted from the radiation source pass through the container truck to detectors, the detectors reflects density distribution of the inspected article according to changes of ray strength and converts ray strength into image gray scale so as to obtain transmission images of the container truck to be inspected.
In the prior art, the radiation imaging systems of this kind are in the following forms: fixed type, combined moveable type and vehicular moveable type. The present invention is a combined mobile radiation imaging system. According to the present applicant's applications for Chinese patent, for example, the application No. 00103342.5 “Detachable combined moveable container detecting apparatus” and application No. 99126240.9 “Combinable moveable container detecting system”, a door-like structure straddling both sides of the container truck to be inspected is provided with a radiation source and detectors, wheels are provided on bottom of the two legs of said door-like structure, said wheels are driven by drive means to allow the scanning device to reciprocatingly move to accomplish scanning. In practical engineering application, this arrangement has the following drawback: since the door-like structure straddling both sides of the container truck to be inspected spans a large distance, which calls for a relatively high requirement for rigidity of the whole of the scanning device and causes great difficulty to design and manufacture of the scanning device. There is a need to improve the overall rigidity of the scanning device. Meanwhile, the large spanning distance makes it very difficult for the wheels on both sides to synchronously run during the whole scanning device operates so that the whole scanning device cannot stably operate and radiation imaging will be affected. Besides, since the mounting structure on the detectors side is provided with wheels underneath, vibration between the wheels and the steel rails affects quality of images.